Pressure-fluid operated tool



Jan. 8, 1957 w. E. NoRTHcUTT 2,776,481

PRESSURE-FLUID OPERTED TOOL Filed July 5, 1956 .MMI

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2,7 7 6 ,481 .Patented:Jansfsiwsv 2,716,481 `lfPRESSURE:Front optimumTooL WaltenEl ANorthcutt,Melrose,.Mass.,. assignor to H. K.

' Porter, Inc.; Somerville, Mass., a corporation of Massa- `cllusetts.,fApplicationtIuly'S; 41956,l Serial\No."595,709

. c4C1aims. (CL :t0-+180) This finve'ntion':y relates ftohydraulicallyoperated tools .'.slich'as those used for; Ec'utting'ste'el l bars` andother heavy ,-work beyond the-range fof 4hand-operated tools, the'object tb'eing .'to provide-"an improved"constructionlforlsuchA a:toolf/whereinameans' are'provid'edflto `prevent entryinto the mechanismof foreign particles with resulting-wear or deterioration of the tool.For instance, in steel mills such tools are use'dfforttrimming'steel rodafter hot rolling, and there is alwaysscale on the rod which is beingcut. As each cut is made small particles of scale are broken away andfall into the opening between the blades and if they are drawn into thebearing surfaces between the moving parts, they may cause cutting orgalling, so that the ram of the tool will stick or the bearings beenlarged until side movement is excessive and the blades will no longerbe in alignment. l

My invention will be well understood by reference to the followingdescription of the illustrative embodiment thereof shown for example inthe accompanying drawings, wherein:

Fig. l is a perspective of the tool;

Fig. 2 is a view chiey in longitudinal section on a larger scale; and

Figs. 3 and 4 are diagrammatic details, unrealistic as to the dimensionsshown.

The tool herein shown is a portable tool in the sense that it may bebrought to the work and may be in part positioned or guided by hand andits cutting cycle is under manual control.

Referring now to the drawings, and more particularly to Fig. 2, thecutting elements of the tool are supported by a C-frame having a fixedcutter 12 mounted on one arm of the C, while the other arm is providedwith a guiding and bearing surface herein formed by a liner or bushing14 for the ram 16 of the hydraulic mechanism on the distal end of whichis mounted a cooperating tool 1S the edge of which, when the ram ismoved to the left from the position of Fig. 2, cooperates with the edgeof the cutter 12 for severing the work.

The C-frarne 10 is herein at least eifectively integral with a head 19closing the left-hand end of a cylinder 20, in which reciprocates asingle acting piston 22, the ram 16 in this instance being the pistonrod. A head 24 closes the right-hand end of the cylinder and forms aworking chamber to which hydraulic fluid may be admitted through thenipple 26 from the flexible conduit 28, Fig. l, leading to a source ofsupply. When the fluid is so admitted the piston 22 moves to the left onthe power stroke and on the exhaust stroke it is returned by thecompression springs 30 interposed between the piston and the head 19. Anorienting pin 32 on the piston enters a hole 34 in the head 19 to orientthe parts.

Referring to Fig. l in the tool shown a ring 36 surrounds the cylinderand provides means for suspending the tool by a flexible connection froman overhead point. A handle 38 mounted von the nipple 26 provides forsteering the tool and a trigger 40 on the handle controls the operationof the hydraulic mechanism. These detrails are here describedbecauseillustratdin"Fig, 1,""but they are 'ofno importance tothe inventionandarenot shown in Fig. 2.

"The" headl 1191 at^the`left`of 'thefc'ylinder' denes with fthe piston achamber of variablesize. -AThe head Yis packed withian O-ring2'42,' but'on movementof the piston to the right air may enter'this chamberthrough. an inwardly opening valve 44'loadedby a"'lightspring. `Ascreena46- and iilter"48-outwardlyl of 'the'valve prevent foreign 10"particles from entering withthe` air.

I Onthe 'exhauststroke' bf thejme'chanismwhen the.' piston moves to the`right a"'charge`of air Vis drawn rinto the chamber. On the returnstroke ythe valve is closed,'fthe `16 andthe-bshing'f 14. "No clearanceis'shown' between these lparts 'in'vv Fig. 2 because that would' bemisleading.

The'control-of this' chargebf air is effected by what is ina sense apacking 50, -although installed reverselyto 'itheusualvmannergandvwhichfunctions also as a'yielding valve. This ring is shown with someexaggeration most clearly in Figs. 3 and 4, and is generally of channelshap'e section with a base 52 and outwardly aring yielding lips 54 and56. The ring may be molded from plastic material of suitable resiliency.I have found nylon to be suitable. I believe also that certain siliconerubbers would serve, but have not fully tested them under conditions ofuse. Tetrafluorethylene is another possibility. This ring may beinstalled in a suitable groove in the ram 16 with the lips projectingaxially outwardly toward the distal or free end of the ram which carriesthe tool 18. In Figs. 3 and 4 the clearance between the ram and thecylinder is much exaggerated. In practice the radial thickness of thebase 52 of the ring may be somewhat smaller than the nominal clearancebetween the bottom of its groove and the liner, say two to livethousandths of an inch. On the other hand the lips may be so molded thatthe distance between them is slightly greater than this nominalclearance, again say two to ve thousandths of an inch, and thereforethey are under a slight compression in Fig. 3. When the ram is movingtoward the right, due to spring pressure, and is exhausting thehydraulic lluid to the right of piston 22 the lip 56 bears on the liner14 and slides over it with a wiping action as shown in Fig. 3. This lipnot only is a mechanical barrier against the entry of foreign matterpast it, but also serves as a Valve, due to the higher pressure outsidethe tool tending to spread the lips of the wiper. It may be noted thatas the piston 22 moves to the right it creates an enlarging volume witha pressure below atmospheric. The reduced pressure within the toolchamber allows outside atmospheric pressure to unseat the ball valve 44until equilibrium of pressures is established, at which point ball valve44 closes.

Now as the piston moves toward the left the valve 44 is closed andpressure begins to build up in the chamber as its volume decreases. Inthe initial stage of the movement the lip 56 will retain the positionshown in Fig. 3 and act as a mechanical wiper or squeegee moving on theliner 14. As pressure builds up however it may ileX inwardly to theposition diagrammed in Fig. 4, permitting ow of air outwardly, and theweb portion S2 of the ring may move downwardly to the bottom of itsgroove, increasing the clearance for air escape past the ring. Thisstream of air tlows outwardly between the bearing surfaces and aroundthe blade 18, lessening the possibility of scale working in between theformer.

I am aware that the invention may be embodied in other specific formswithout departing from the spirit or essential attributes thereof, and Itherefore desire the present embodiment to be considered in all respectsas illustrative and not restrictive, as is in fact clear in severalmatters from the description itself. Reference is to be had to theappended claims to indicate those principles of the inventionexemplified by the particular embodiment described and which I desire tosecure by Letters Patent.

I claim:

1. A pressure-fluid operated tool comprising a cylinder having a pistontherein, a ram carried by the piston having a tool mounted thereon, aclosure head for the cylinder through which the ram passes definingwithin the cylinder an air receiving chamber, guiding means for the ram,an inwardly opening valve for admitting air to the chamber on theexhaust stroke of the piston and yieldable means p providing fordischarge of entrapped air from the chamber over the guiding surfaces onthe power stroke of the piston.

2. A pressure-Huid operated tool comprising a cylinder having a pistontherein, a tool-carrying member carried by the piston, a closure headfor the cylinder through which said member passes defining within thecylinder an air receiving chamber, means associated with the headproviding an elongated external bearing for said member, a tool on theend of said member and packing means between said member and bearinghaving a resiliently ilexible axially outwardly extending lip whichbears on one of them during the exhaust stroke to exclude passage of airto the chamber during the exhaust stroke and yields to permit passage ofair over the bearing surfaces during the power stroke.

3. A pressure-fluid operated tool comprising a cylinder having a pistontherein, a ram carried by the piston having a tool at its distal end abearing in which the ram slides, a packing ring between ram and bearinghaving a lip extending axially outwardly and resiliently yieldableradially inwardly, means controlled by movement of the piston fordrawing in a charge of air on one stroke of the piston and means forreleasing it to the bearing surfaces at the inward side of the lip onthe other stroke.

4. A tool comprising a frame having a pair of cooperating cuttersmounted thereon one being mounted on a ram to move to and from theother, the frame having a bearing for supporting and guiding the ram, apacking between bearing and ram adjacent the tool normally biased toexclude passage of air therethrough from the tool side but yieldable topressure from the other side, pressure-duid operated means forreciprocating the ram, and means operated thereby for discharging airunder pressure to the bearing surfaces at said other side of thepacking.

No references cited.

